One of our toilets is not draining right. It fills with water and then drains down fast enough for it to swirl, but not really enough to pull a piece of toilet paper. I tried a plunger with no change. Eventually all the water drains out. It's in the basement. When you flush another toilet you can hear it making sounds (bubbling/gurgling). I thought maybe it's clogged further down the line. I was going to buy a snake and see if that helped. This morning we found some water by our furnace room. I assume it came up through the drain. It was dry around the drain, but I could see water above the trap. I also realized instead of turning the in-line humidifier off I had turned it up to 100 a few weeks ago. The heat has been on some over the last week, but I don't think enough to fill the drain. I checked the sump and it's dry. We had one light rain over the last week or so.

Any thoughts? I was going to call a plumber we've used, unfortunately they don't work on weekends.